1. Technical Field
The present invention relates to a radio communication system that conducts radio communication between a radio base station and a radio communication terminal, as well as to a radio base station and a radio communication terminal therefor.
2. Background Art
Telecommunication carriers provide various communication services by means of establishing; for instance, a mobile communication network and implementing a mobile communication service for a portable phone, and the like. When utilizing a radio communication link, the communication carriers are allowed to utilize frequencies only at an allocated frequency. Therefore, maximum effective utilization of the allocated frequency has been desired under recent circumstances where communication traffic is on the increase.
Example effective utilization of the allocated frequency is a bandwidth switching technique disclosed in; for instance, JP-A-2010-118853. The bandwidth switching technique aims at controlling allocation of a frequency band for an uplink data communication and a frequency band for a downlink data communication on the basis of occupancies of respective channels in a frequency band and a free bandwidth, thereby effectively utilizing an uplink frequency band and a downlink frequency band.
By way of example, there is provided an assumption that, in a radio communication system which configures a mobile communication network by means of arranging radio base stations at a plurality of sites, a telecommunication carrier divides frequency resources and allocates the divided resources to a plurality of users connected to one radio base station. On this occasion, assuring an individual user of the minimum throughput results in a reduction in the number of users concurrently connected. Difficulty is encountered in accomplishing both provision of the minimum guaranteed throughput and an increase in the number of users concurrently connected. In reality, it is hard to realize an application field where setting of the minimum guaranteed throughput is desired.
The example described in connection with JP-A-2010-118853 is intended for effectively utilizing frequency resources within an allocated frequency band, and effective utilization of the frequency resources can be implemented within the allocated frequency band. However, when a free bandwidth does not exist in the allocated frequency band, difficulty is encountered in accomplishing both provision of the minimum guaranteed throughput and an increase in the number of users concurrently connected.
The present invention has been conceived in light of the circumstances and aims at making it possible to assure in radio communication the throughput and the number of users concurrently connected at a maximum depending on the situation without being restricted to a bandwidth of currently allocated frequencies.